Also clean up the comments formatting for generate_stats.py

Bug: angleproject:3369
Change-Id: Ifaa26cb898915038cf47e88341db5057b59dd937
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1588315
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>